The present invention relates to a damper.
In Patent Reference No. 1, as shown in FIG. 7, a rotor 102 is disposed in a body case 100, and a silicone grease as a viscous fluid is filled in a space between the body case 100 and the rotor 102 sealed by a cap 104.
The rotor 102 is provided with a clutch disc 106 to be rotatable with the rotor. Another clutch disc 108 is provided on an upper part of the clutch disc 106. Incidentally, a lid member 105 can engage the cap 104, and an engaging portion 107 projecting from the lid member 105 is exposed through a through-hole 104A formed at the center of the cap 104.
Also, the clutch disc 108 is attached to a back surface of the lid member 105 so that the clutch disc 108 can rotate with the lid member 105 and move in an axial direction of the lid member 105. Further, a coil spring 110 is disposed between the back surface of the lid member 105 and the clutch disc 108 for urging the clutch disc 108 to a side of the clutch disc 106.
Here, a spur wheel 114 is fixed to the engaging portion 107 of the lid member 105 to transmit a rotational force from the spur wheel 114. Therefore, when the spur wheel 114 is rotated in an arrow direction A, a teeth portion 106A of the clutch disc 106 engages a teeth portion 108A of the clutch disc 108 to thereby rotate the rotor 102. Thus, the rotor 102 receives a viscous resistance due to the silicone grease to damp the rotation of the spur wheel 114 through the clutch discs 106 and 108.
On the other hand, when the spur wheel 114 is rotated in the direction opposite to the arrow direction A, since the teeth portion 106A of the clutch disc 106 does not engage the teeth portion 108A of the clutch disc 108, the clutch disc 108 moves in the axial direction of the lid member 105. Thus, the clutch disc 106 rotates idly with respect to the clutch disc 108, and the rotor 102 does not rotate. Therefore, the spur wheel 114 is rotated without receiving the viscous resistance.
Therefore, it is possible to apply or release the braking force to the braking member through the engagement between the spur wheel and a gear at the braking member side, not shown.
However, in the damper described above, the number of parts and assembling work are increased, thereby increasing a cost. Also, by using the clutch discs 106 and 108 with the teeth portions 106A and 108A, when the rotational force is transmitted to the clutch disc 106 from the driving clutch plate 108, there may be a time lag depending on an engagement state of the teeth portions 106A and 108A.
Patent Reference No. 1
Japanese Utility Model (Jikkai) No. 05-89993 (refer to Pages 9-13, FIG. 1)
In view of the above problems, the present invention has been made, and an object of the invention is to provide a damper, wherein a torque can be changed according to a rotational direction with a simple structure.
Further objects and advantages of the invention will be apparent from the following description of the invention.